1,1,1,2-tetrafluoroethane as a blowing agent in integral skin polyurethane shoe soles

ABSTRACT

It has been found that 1,1,1,2-tetrafluoroethane (HFC-134a) may be used alone or in combination with water as blowing agents in flexible integral skin foams. Foams prepared using HFC-134a alone or in combination with water exhibit physical characteristics such as resistance to abrasion and cracking on flex comparable to conventional chlorinated fluorocarbon blown foams. The foams of the present invention are suitable for use in shoe sole applications.

This is a division of application U.S. Ser. No. 08/442,235, filed May15, 1995, now U.S. Pat. No. 5,506,275, which is a divisional of U.S.Ser. No. 07/999,632, filed Dec. 31, 1992, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to an integral skin polyurethane foamcomposition and a process for preparing said foam. In particular, theinvention relates to those foams utilizing 1,1,1,2-tetrafluoroethane(HFC-134a) alone or as a co-blowing agent with water, which are usefulin shoe sole applications. The use of HFC-134a and optionally waterobviates the need to use the ozone depleting chlorofluorocarbons inpolyurethane shoe sole system.

DESCRIPTION OF THE RELATED ART

Integral skin foams are well known to those skilled in the art ofpolyurethane foams. Such foams have a cellular interior and a higherdensity microcellular or non-cellular skin. In general, to prepare suchfoams one reacts an organic isocyanate with a substance having at leastone isocyanate reactive group in the presence of a catalyst, blowingagent, and a variety of optional additives. The reaction is carried outin a mold where a higher density skin forms at the interface of thereaction mixture and the relatively cool inner surface of the foam.

At the present time, the most common type of blowing agent used inintegral skin polyurethane foams is chlorofluorocarbons (CFCs) orcombinations of CFCs and other blowing agents. Industry today, however,is faced with a mandate to reduce and eventually eliminate the use ofCFCs. To this end, much energy is being devoted.

Past methods of preparing integral skin polyurethanes with CFCs as ablowing agent includes G.B. Patent No. 1,209,297, which teaches the useof a combination blowing agent consisting of a CFC and hydrate of anorganic compound which splits off water at temperatures above 40° C.This blowing agent or combination of agents was used in a formulationwith a suitable polyisocyanate, a polyol-containing hydroxyl group, anda catalyst. This patent discloses the undesirability of having freewater in the system. The patent states that the presence of even smallquantities of water produce a skin that is permeated with fine cells.

U.S. Pat. No. 4,305,991 describes a process for preparing integral skinpolyurethane foams wherein a polyisocyanate containing aliphaticallyand/or cycloaliphatically bound isocyanate groups is reacted withpolyhydroxyl compounds containing ether linkages, a chain extender, acatalyst, additives, and a blowing agent. The blowing agent ischaracterized as a readily volatile organic substances, examples ofwhich include both halogenated and non-halogenated volatile organiccompounds to which water may be added as a chemical blowing agent.

More recently, attempts have been made to evaluate the performance ofalternate blowing agents to CFCs. In a paper by J. L. R. Clatty and S.J. Harasin entitled, Performance of Alternate Blowing Agents toChlorofluorocarbons in RIM Structural and Elastomeric PolyurethaneFoams, presented to the 32nd Annual Polyurethane Technical/MarketingConference, October 1989, the authors addressed the use of water as ablowing agent for integral skin polyurethane reaction injection moldedsystems (RIM). In this application, the water concentration in thesystem is controlled by the concentration and type of molecular sievesused: As in the Great Britain patent discussed previously, the water isnot in a free form but bound in some manner. In this instance, theauthors state that this process is limited to use in rigid foam systems;and the flexible integral skin formulations may best be served by usingHCFCs or HCFC-22 as substitutes for CFCs.

Integral skin foams prepared for use in shoe soles must not only have acosmetically acceptable appearance but must also exhibit enhancedresistance to abrasion and cracking on flex. It has been found thatfoams utilizing HFC-134a as the blowing agent alone or in combinationwith water can be prepared which meet the stringent requirementsinherent in shoe sole applications.

SUMMARY OF THE INVENTION

Prior processes have used CFCs, HCFCs, volatile organic alkanes such aspentane and heptane, and water either alone or in combination as theblowing or density control agent in integral skin polyurethane foams.

It is the object of the present invention to provide a flexible, lowdensity, integral skin polyurethane foam capable of use in shoe soleapplications; wherein, the integral skin foam uses no CFCs, HCFCs, orvolatile organic alkanes such as pentane or heptane as blowing agents.This flexible integral skin foam, comprises:

A) a polyisocyanate component,

B) isocyanate reactive polyols having a functionality of at least 1.5,

C) 1,1,1,2-tetrafluoroethane as a blowing agent,

D) optionally, water as a co-blowing agent,

E) a catalyst capable of promoting urethane formation,

F) a chain extender,

G) optionally a surfactant,

H) optionally an essentially linear alcohol having from 10 to 20carbons, and

I) optionally fillers, pigments, antioxidants, and stabilizers.

The general process comprises reacting a polyisocyanate component withan isocyanate reactive compound. This is done in the presence of acatalyst of a type known by those skilled in the art in sufficientquantity to catalyze the reaction, 1,1,1,2-tetrafluoroethane in anamount sufficient to act as a blowing agent or optionally as aco-blowing agent with water; a surfactant which when used acts not onlyas a cell regulating agent but also as an emulsifying agent to keep thegaseous HFC-134a in solution; a chain extender; and optionally a C₁₀₋₂₀alcohol, fillers, pigments, antioxidants, and stabilizers.

The organic polyisocyanates used in the instant process containaromatically bound isocyanate groups. Representative of the types oforganic polyisocyanates contemplated herein include, for example,1,4-diisocyanatobenzene, 1,3-diisocyanato-o-xylene,1,3-diisocyanato-p-xylene, 1,3-diisocyanato-m-xylene,2,4-diisocyanato-1-chlorobenzene,2,4-diisocyanato-1-nitrobenzene,2,5-diisocynato-1-nitrobenzene,m-phenylenediisocyanate,2,4-toluene diisocyanate, 2,6-toluene diisocyanate,mixtures of 2,4- and 2,6-toluene diisocyanate, hexahydrotoluenediisocyanate, 1,5-naphthalene diisocyanate, 1-methoxy-2,4-phenylenediisocyanate, 4,4'-biphenylmethane diisocyanate, 4,4'-biphenylenediisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate,3,3'-4,4'-diphenylmethane diisocyanate, and3,3'-dimethyldiphenylmethane-4,4'-diisocyanate; the triisocyanates suchas 4,4',4"-triphenylmethane triisocyanate, polymethylene polyphenylenepolyisocyanate, and 2,4,6-toluene triisocyanate; and thetetraisocyanates such as 4,4-dimethyl-2,2'-5,5'-diphenylmethanetetraisocyanate. Especially useful due to their availability andproperties are 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethanediisocyanate, polymethylene polyphenylene polyisocyanate, and mixturesthereof.

These polyisocyanates are prepared by conventional methods known in theart such as the phosgenation of the corresponding organic amine.Included within the usable isocyanates are the modifications of theabove isocyanates which contain carbodiimide, allophanate, alkylene, orisocyanurate structures. Quasi-prepolymers may also be employed in theprocess of the subject invention. These quasi-prepolymers are preparedby reacting an excess of organic polyisocyanate or mixtures thereof witha minor amount of an active hydrogen containing compound determined bythe well-known Zerewitinoff Test, as described by Kohler in Journal ofthe American Chemical Society, 49, 3181 (1927). These compounds andtheir methods of preparation are well known in the art. The use of anyone specific active hydrogen compound is not critical hereto; rather,any such compound can be employed herein. Generally, thequasi-prepolymers have a free isocyanate content of from 20 percent to40 percent by weight.

Mixtures of polymeric diphenylmethane diisocyanate (polymeric-MDI) andcarbodiimide or urethane-modified MDI are preferred.

Any suitable polyoxyalkylene polyether polyol may be used such as thoseresulting from the polymerization of a polyhydric alcohol and analkylene oxide. Representatives of such alcohols may include ethyleneglycol, propylene glycol, trimethylene glycol, 1,2-butanediol,1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,4-pentanediol,1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, glycerol,1,1,1-trimethylolpropane, 1,1,1-trimethylolethane, or 1,2,6-hexanetriol.Any suitable alkylene oxide may be used such as ethylene oxide,propylene oxide, butylene oxide, amylene oxide, and mixtures of theseoxides. The polyoxyalkylene polyether polyols may be prepared from otherstarting materials such as tetrahydrofuran and alkyleneoxide-tetrahydrofuran mixtures, epihalohydrins such as epichlorohydrin,as well as aralkylene oxides such as styrene oxide. The polyoxyalkylenepolyether polyols may have either primary or secondary hydroxyl groups.Included among the polyether polyols are polyoxyethylene glycol,polyoxypropylene glycol, polyoxybutylene glycol polytetramethyleneglycol, block copolymers, for example, combinations of polyoxypropyleneand polyoxyethylene glycols, poly-1,2-oxybutylene and polyoxyethyleneglycols and copolymer glycols prepared from blends or sequentialaddition of two or more alkylene oxides. The polyoxyalkylene polyetherpolyols may be prepared by any known process, such as the processdisclosed by Wurtz in 1859 and Encyclopedia of Chemical Technology, Vol.7, pp. 257-262, published by Interscience Publishers, Inc. (1951) or inU.S. Pat. No. 1,922,459.

Other polyoxyalkylene polyether polyols which may be employed are thosewhich contain grafted therein vinylic monomers.

The polyols which have incorporated therein the vinylic polymers may beprepared (1) by the in situ free-radical polymerization of anethylenically unsaturated monomer or mixture of monomers in a polyol, or(2) by dispersion in a polyol of a preformed graft polymer prepared byfree-radical polymerization in a solvent such as described in U.S. Pat.Nos. 3,931,092; 4,014,846; 4,093,573; and 4,122,056; the disclosures ofwhich are herein incorporated by reference, or (3) by low temperaturepolymerization in the presence of chain transfer agents. Thesepolymerizations may be carried out at a temperature between 65° C. and170° C., preferably between 75° C. and 135° C.

The amount of ethylenically unsaturated monomer employed in thepolymerization reaction is generally from one percent to 60 percent,preferably from 10 percent to 40 percent, based on the total weight ofthe product. The polymerization occurs at a temperature between about80° C. and 170° C., preferably from 75° C. to 135° C.

The polyols which may be employed in the preparation of the graftpolymer dispersions are well known in the art. Both conventional polyolsessentially free from ethylenic unsaturation such as those described inU.S. Pat. No. Re. 28,715 and unsaturated polyols such as those describedin U.S. Pat. Nos. 3,652,659 and Re. 29,014 may be employed in preparingthe graft polymer dispersions used in the instant invention, thedisclosures of which are incorporated by reference.

Representative polyols essentially free from ethylenic unsaturationwhich may be employed are well known in the art. They are often preparedby the catalytic condensation of an alkylene oxide or mixture ofalkylene oxides either simultaneously or sequentially with an organiccompound having at least two active hydrogen atoms such as evidenced byU.S. Pat. Nos. 1,922,459; 3,190,927; and 3,346,557, the disclosures ofwhich are incorporated by reference.

The unsaturated polyols which may be employed for preparation of graftcopolymer dispersions may be prepared by the reaction of anyconventional polyol such as those described above with an organiccompound having both ethylenic unsaturation and a hydroxyl, carboxyl,anhydride, isocyanate, or epoxy group; or they may be prepared byemploying an organic compound having both ethylenic unsaturation and ahydroxyl, carboxyl, anhydride, or epoxy group as a reactant in thepreparation of the conventional polyol. Representative of such organiccompounds include unsaturated mono- and polycarboxylic acids andanhydrides such as maleic acid and anhydride, fumaric acid, crotonicacid and anhydride, propenyl succinic anhydride, and halogenated maleicacids and anhydrides, unsaturated polyhydric alcohols such as2-butene-1,4-diol, glycerol allyl ether, trimethylolpropane allyl ether,pentaerythritol allyl ether, pentaerythritol vinyl ether,pentaerythritol diallyl ether, and 1-butene-3,4-diol, unsaturatedepoxides such as 1-vinylcyclohexene monoxide, butadiene monoxide, vinylglycidyl ether, glycidyl methacrylate and 3-allyloxypropylene oxide.

As mentioned above, the graft polymer dispersions used in the inventionare prepared by the in situ polymerization of an ethylenicallyunsaturated monomer or a mixture of ethylenically unsaturated monomer ora mixture of ethylenically unsaturated monomers, either in a solvent orin the above-described polyols. Representative ethylenically unsaturatedmonomers which may be employed in the present invention includebutadiene, isoprene, 1,4-pentadiene, 1,5-hexadiene, 1,7-octadiene,styrene, α-methylstyrene, methylstyrene, 2,4-dimethylstyrene,ethylstyrene, isopropylstyrene, butylstyrene, phenylstyrene,cyclohexylstyrene, benzylstyrene, and the like; substituted styrenessuch as chlorostyrene, 2,5-dichlorostyrene, bromostyrene, fluorostyrene,trifluoromethylstyrene, iodostyrene, cyanostyrene, nitrostyrene, N,N-dimethylaminostyrene, acetoxystyrene, methyl-4-vinylbenzoate,phenoxystyrene, p-vinyldiphenyl sulfide, p-vinylphenyl phenyloxide, andthe like; the acrylic and substituted acrylic monomers such asacrylonitrile, acrylic acid, methacrylic acid, methylacrylate,2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, methylmethacrylate, cyclohexyl methacrylate, benzyl methacrylate, isopropylmethacrylate, octyl methacrylate, methacrylonitrile, methylα-chloroacrylate, ethyl α-ethoxyacrylate, methyl α-acetam, inoacrylate,butyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, phenylmethacrylate, α-chloroacrylonitrile, methacrylonitrile,N,N-dimethylacrylamide, N,N-dibenzylacrylamide, N-butylacrylamide,methacryl formamide, and the like; the vinyl esters, vinyl ethers, vinylketones, etc., such as vinyl acetate, vinyl chloroacetate, vinylalcohol, vinyl butyrate, isopropenyl acetate, vinyl formate, vinylacrylate, vinyl methacrylate, vinyl methoxyacetate, vinyl benzoate,vinyl iodide, vinyltoluene, vinylnaphthalene, vinyl bromide, vinylfluoride, vinylidene bromide, 1-chloro-1-fluoroethylene, vinylidenefluoride, vinyl methyl ether, vinyl ether, vinyl propyl ether, vinylbutyl ether, vinyl 2-ethylhexyl ether, vinyl phenyl ether, vinyl2-butoxyethyl ether, 2,4-dihydro-1,2-pyran, 2-butoxy-2'-vinyloxy diethylether, vinyl 2-ethylthioethyl ether, vinyl methyl ketone, vinyl ethylketone, vinyl phenyl ketone, vinyl phosphonates such asbis(β-chloroethyl)vinyl phosphonate, vinyl ethyl sulfide, vinyl ethylsulfone, N-methyl-N-vinyl acetamide, N-vinyl pyrrolidone, vinylimidazole, divinyl sulfide, divinyl sulfoxide, divinyl sulfone, sodiumvinylsulfonate, methyl vinylsulfonate, N-vinyl pyrrole, and the like;dimethyl fumarate, dimethyl maleate, maleic acid, crotonic acid, fumaricacid, itaconic acid, monomethyl itaconate, butylaminoethyl methacrylate,dimethylaminoethyl methacrylate, glycidyl acrylate, allyl alcohol,glycol monoesters of itaconic acid, dichlorobutadiene, vinyl pyridine,and the like. Any of the known polymerizable monomers can be used, andthe compounds listed above are illustrative and not restrictive of themonomers suitable for use in this invention. Preferably, the monomer isselected from the group consisting of acrylonitrile, styrene, methylmethacrylate, and mixtures thereof.

Illustrative initiators which may be employed for the polymerization ofvinyl monomers are the well-known free radical types of vinylpolymerization initiators, for example, the peroxides, persulfates,perborates, percarbonates, azo compounds, etc., including hydrogenperoxide, dibenzoyl peroxide, acetyl peroxide, benzoyl hydroperoxide,t-butyl hydroperoxide, di-t-butyl peroxide, lauroyl peroxide, butyrylperoxide, diisopropylbenzene hydroperoxide, cumeme hydroperoxide,paramenthane hydroperoxide, di-α-cumyl-peroxide, dipropyl peroxide,diisopropyl peroxide, difuroyl peroxide, ditriphenylmethyl peroxide,bis(p-methoxybenzoyl) peroxide, p-monoethoxybenzoyl peroxide, rubeneperoxide, ascaridol, t-butyl peroxybenzoate, diethylperoxyterephthalate, propyl hydroperoxide, isopropyl hydroperoxide,n-butyl hydroperoxide, cyclohexyl hydroperoxide, trans-decalinhydroperoxide, α-methylbenzyl hydroperoxide, α-methyl-α-ethyl benzylhydroperoxide, tetralin hydroperoxide, triphenylmethyl hydroperoxide,diphenylmethyl hydroperoxide, α,α'-azobis(2-methyl)heptonitrile,1,1-azo-bis(1-cyclohexane)carbonitrile, dimethylα,α'-azobis(isobutyronitrile), 4,4'-azobis(cyanopetanoic) acid,azobis(isobutyronitrile), 1-t-amylazo-1-cyanocyclohexane,2-t-butylazo-2-cyano-4-methoxy-4-methylpentane,2-t-butylazo-2-cyano-4-methylpentane, 2-(t-butylazo)isobutyronitrile,2-t-butylazo-2-cyanobutane, 1-cyano-1-(t-butylazo)cyclohexane, t-butylperoxy-2-ethylhexanoate, t-butyl perpivalate,2,5-dimethylhexane-2,5-diper-2-ethylhexoate, t-butylperneo-decanoate,t-butyl perbenzoate, t-butyl percrotonate, persuccinic acid, diisopropylperoxydicarbonate, and the like; a mixture of initiators may also beused. Photochemically sensitive radical generators may also be employed.Generally from about 0.5 percent to about 10 percent, preferably fromabout 1 percent to about 4 percent, by weight of initiator based on theweight of the monomer will be employed in the final polymerization.

Stabilizers may be employed during the process of making the graftpolymer dispersions. One such example is the stabilizer disclosed inU.S. Pat. No. 4,148,840, which comprises a copolymer having a firstportion composed of an ethylenically unsaturated monomer or mixture ofsuch monomers and a second portion which is a propylene oxide polymer.Other stabilizers which may be employed are the alkylene oxide adductsof copolymers of styrene-allyl alcohol.

The preferred polyols are polyethers having an average functionality ofabout 1.75 to about 3.0 and a molecular weight range of from about 3500to about 5100. The most preferred polyols are polyethers which arecopolymers of ethylene oxide and propylene oxide having a diol or triolinitiator such as propylene glycol glycerine or trimethylolpropane.Included with this group are the previously described graft polymerdispersions.

Any suitable catalyst may be used including tertiary amines such astriethylenediamine, N-methylmorpholine, N-ethylmorpholine,diethylethanolamine, N-cocomorpholine,1-methyl-4-dimethylaminoethylpiperazine, methoxypropyldimethylamine,N,N,N'-trimethylisopropyl propylenediamine,3-diethylaminopropyldiethylamine, dimethylbenzylamine, and the like.Other suitable catalysts are, for example, dibutyltin dilaurate,dibutyltin diacetate, stannous chloride, dibutyltin di-2-ethylhexanoate, stannous oxide, available under the FOMREZ® trademark, aswell as other organometallic compounds such as are disclosed in U.S.Pat. No. 2,846,408.

An alcohol having from about 10 to about 20 carbons or mixtures thereofmay be used in the present invention. Alcohols of this type are known tothose skilled in the art. The types of alcohols contemplated arecommonly produced via the oxo process and are referred to asoxo-alcohols. Examples of some commercially available products includeLIAL 125 from Chemica Augusta Spa or NEODOL® 25 produced by Shell.

A surface active agent is generally used for production of integral skinpolyurethane foams of the present invention. Surfactants which may beused are those which aid in homogenizing or emulsifying the initialmaterials and may also be suitable for regulating cell structure.Typical examples are foam stabilizers such as siloxane oxyalkyleneheterol polymers and other organic polysiloxanes, oxyethylated alkylphenol, oxyethylated fatty alcohols, fluoroaliphatic polymeric esters,paraffin oils, castor oil ester, phthalic acid esters, ricindolic acidester, and Turkey red oil, as well as cell regulators such as paraffins.

Chain extending agents employed in the present invention include thosehaving two functional groups bearing active hydrogen atom. A preferredgroup of chain extending agents includes ethylene glycol, diethyleneglycol, propylene glycol, or 1,4-butanediol.

Additives which may be used in the process of the present inventioninclude known pigments, such as carbon black, dyes, and flame retardingagents (e.g., tris-chloroethyl phosphates or ammonium phosphate andpolyphosphate), stabilizers against aging and weathering, plasticizers,such as gamma butylactone, fungistatic and bacteriostatic substances,and fillers.

The main blowing and density controlling agent used according to thepresent invention is 1,1,1,2-tetrafluoroethane (HFC-134a). For thepurpose of the invention, water may also be present in amounts up to andincluding 0.2 percent by weight based on the total weight of thenonisocyanate components. HFC-134a is used either alone or inconjunction with water in amounts sufficient to provide the desired foamdensity. For foams having sectional densities of from 25 per to about 35pcf, the amount of HFC-134a used as the sole blowing agent will rangefrom about 1.5 to about 6.0 percent by weight with the amount reducedwhen water is added as a co-blowing agent. When water is present inamounts of 0.05 to 0.1 percent by weight, the preferred range ofHFC-134a is 1.5 to 2.5 percent by weight of the non-isocyanatecomponents total weight.

The mechanical parameters of the instant process are flexible and dependon the final application of the integral skin polyurethane foam. Thereaction system is versatile enough that it may be made in a variety ofdensities and hardnesses. The system may be introduced into a mold in avariety of ways known to those skilled in the art. It may be shot into apreheated closed mold via high pressure injection technique. In thismanner, it processes well enough to fill complex molds at low molddensities (from 18 pcf to 25 pcf). It may also be run using aconventional open mold technique wherein the reaction mixture or systemis poured or injected at low pressure or atmospheric pressure into apreheated open mold. In the instant process, the system may be run atmold temperatures from about room temperature to about 120° F. with roomtemperature being preferred.

Having thus described the invention, the following examples are given byway of illustration. All mounts are given in parts by weight unlessotherwise indicated.

    ______________________________________                                        Test Methods                                                                  ______________________________________                                        Density ASTM D-1622                                                                             Split Tear ASTM D-1938                                      Tensile Strength ASTM D-412                                                                     Graves Tear ASTM D-42 Die C                                 Tensile Elongation ASTM D-412,                                                                  Shore Hardness ASTM D-2240                                  Die A                                                                         Taber Abrasion ASTM 1044                                                                        Ross Flex ASTM 1052                                         ______________________________________                                    

Polyol A is a propylene glycol initiated polyoxypropylenepolyoxyethylene block copolymer having a hydroxyl number of about 25 anda molecular weight of about 3850.

Polyol B is a 31 percent solids, 1:1, acrylonitrile:styrene graftcopolymer dispersed, in a trimethylolpropane initiatedpolyoxypropylene-polyoxyethylene block copolymer having a molecularweight of about 4120. The graft polymer dispersion has a hydroxyl numberof about 25.

Polyol C is a glycerine initiated polyoxypropylene-polyoxyethylene blockcopolymer having a hydroxyl number of about 27 and a molecular weight ofabout 5050.

FSO 100 is a telomer B monoether with polyethylene glycol, containingfrom 0.05 to 0.2 percent 1,4-dioxane. It is available from DuPont.

L-12771 is fluoroaliphatic polymeric esters used as anemulsifier/surfactant. It is available from 3M.

FC-126 is 80 to 90 percent ammonium perfluoro-octanate and 6 to 12percent lower perfluoro-alkyl carboxylate salt used as anemulsifier/surfactant. It is available from 3M.

DC-193 is a silicone surfactant available from Dow.

FC-430 is fluoroaliphatic polymeric esters used as anemulsifier/surfactant. It is available from 3M.

FC-171 is 50 percent aromatic naphtha and 50 percent fluoroaliphaticpolymeric esters used as an emulsifier/surfactant. It is available from3M.

FC-431 is fluoroaliphatic polymeric esters used as anemulsifier/surfactant. It is available from 3M.

I-460 is an amine catalyst blend of 25 percent triethylene diamine in 75percent butanediol.

FC-740 is a fluorinated alkyl alkoxylate used as anemulsifier/surfactant. It is available from 3M.

XFE-1028 is an amine catalyst comprising a proprietary blend availablefrom Air Products.

T-12 is dibutyltin dilaurate.

L-5440 is a silicone surfactant available from Union Carbide.

X2-5394 is a silicone surfactant, specifically methyl(polyethyleneoxide)bis(trimethylsiloxy)silane and polyethylene oxide allyl ether,available from Air Products.

HFC-134a is 1,1,1,2-tetrafluoroethane.

Iso A is a solvent-free 50/50 weight percent blend of diphenylmethanediisocyanate and a urethane-modified polymethylenepolyphenylpolyisocyanate prepolymer, wherein the blend has an isocyanatecontent of 23 weight percent.

                                      TABLE 1                                     __________________________________________________________________________                      1    2     3    4                                           __________________________________________________________________________    SAMPLE                                                                        POLYOL A          119.1                                                                              117.5 116.0                                                                              114.4                                       POLYOL B          38.6 35.08 37.58                                                                              37.08                                       POLYOL C          13.79                                                                              13.60 13.42                                                                              13.24                                       1,4-BUTANEDIOL    11.95                                                                              11.79 11.63                                                                              11.48                                       ETHYLENE GLYCOL   0.367                                                                              0.362 0.358                                                                              0.353                                       XFE-1028          2.025                                                                              1.998 1.972                                                                              1.946                                       T-12              0.089                                                                              0.088 0.087                                                                              0.086                                       L-5440            0.367                                                                              0.362 0.358                                                                              0.353                                       HFC-134a          4.759                                                                              4.694 4.632                                                                              4.571                                       ISO A - - - INDEX/AMOUNT                                                                        100/71.87                                                                          105/74.44                                                                           110/76.95                                                                          115/79.39                                   PHYSICALS                                                                     SECTIONAL DENSITY (pcf)                                                                         32.01                                                                              31.44 31.42                                                                              31.6                                        TENSILE STRENGTH (psi)                                                                          337  326.6 336  308                                         ELONGATION % AT BREAK                                                                           310  226.6 200  156.6                                       SPLIT TEAR (pi)   50.1 40.1  32.7 32.7                                        GRAVES TEAR (pi)  97.0 86.6  76.0 73.1                                        SHORE HARDNESS    54   52    54   65                                          TABER ABRASION (mg. lost, 18 wheel)                                                             199.4                                                                              126.7 110.7                                                                              89.4                                        ROSS FLEX                                                                     K CYCLES TO FAIL  0    0     17.4 15                                          % CRACK AT FAIL   0    0     --   --                                          __________________________________________________________________________     **    equals failure.                                                    

                                      TABLE 2                                     __________________________________________________________________________                  1    2    3    4    5    6   7    8    9    10                  __________________________________________________________________________    SAMPLES                                                                       POLYOL A      126.7                                                                              126.7                                                                              126.7                                                                              126.7                                                                              126.7                                                                              126.7                                                                             126.7                                                                              126.7                                                                              126.7                                                                              126.7               POLYOL B      37.9 37.9 37.9 37.9 37.9 37.9                                                                              37.9 37.9 37.9 37.9                POLYOL C      13.3 13.3 13.3 13.3 13.3 13.3                                                                              13.3 13.3 13.3 13.3                1,4-BUTANEDIOL                                                                              11.4 11.4 11.4 11.4 11.4 11.4                                                                              11.4 11.4 11.4 11.4                ETHYLENE GLYCOL                                                                             0.38 0.38 0.38 0.38 0.38 0.38                                                                              0.38 0.38 0.38 0.38                SURFACTANT 1-10                                                                             0.38 0.38 0.57 0.57 0.57 0.57                                                                              0.57 0.57 0.57 0                   XFE-1028      1.9  1.9  1.9  1.9  1.9  1.9 1.9  1.9  1.9  1.9                 T-12          0.147                                                                              0.147                                                                              0.147                                                                              0.147                                                                              0.147                                                                              0.147                                                                             0.147                                                                              0.147                                                                              0.147                                                                              0.147               I-460         0.46 0.46 0.46 0.46 0.46 0.46                                                                              0.46 0.46 0.46 0.46                HFC-134a      4.9  4.9  4.9  4.9  4.9  4.9 4.9  4.9  4.9  4.9                 ISOCYANATE INDEX                                                                            69.0 69.0 69.0 69.0 69.0 69.0                                                                              69.0 69.0 69.0 69.0                100/ISO A                                                                     PHYSICALS                                                                     SECTIONAL DENSITY (pcf)                                                                     26.9 29.3 29.5 29.7 27.8 29.9                                                                              28.6 30.2 28.7 28.6                TENSILE STRENGTH (psi)                                                                      185.5                                                                              130  151.5                                                                              155  191  144 193  164.5                                                                              108.3                                                                              174                 ELONGATION % AT BREAK                                                                       220  157.5                                                                              170  175  235  187.5                                                                             245  179.5                                                                              150  207                 SPLIT TEAR (pi)                                                                             40   34.4 40.9 47.3 33.8 19  34.6 39.6 34.6 33.5                GRAVES TEAR (pi)                                                                            66.9 58.5 64.5 53.7 76.6 53.9                                                                              60.2 70.6 52.1 62.4                SHORE HARDNESS                                                                              40   43   44   48   42   45  43   44   44   41                  TABER ABRASION (mg.                                                                         210.1                                                                              641.3                                                                              86.8 125.8                                                                              116.2                                                                              132.5                                                                             23.6 48   50.3 167.6               LOST, 18 WHEEL)                                                               ROSS FLEX                                                                     K CYCLES TO FAIL (500%                                                                      >100 46   >100 >100 >100 51  >100 100  >100 >100                CRACK)                                                                        % CRACK AT 100 K CYCLES                                                                     0    --   0    0    0    --  0    --   0    0                   __________________________________________________________________________     1-10 SURFACTANTS USED IN EX. 1-10: 1 = DC193; 2 = L5440; 3 = FC431; 4 =       FC126; 5 = L12771; 6 = FC171; 7 = FC740; 8 = FC430; 9 = FSO100; 10 = NO       SURFACTANT.                                                                   **    equals failure.                                                    

                                      TABLE 3                                     __________________________________________________________________________                  1    2    3    4    5    6    7    8    9   10                  __________________________________________________________________________    SAMPLES                                                                       POLYOL A      123.74                                                                             123.2                                                                              122.3                                                                              121.94                                                                             121.41                                                                             121.04                                                                             120.56                                                                             120.09                                                                             119.37                                                                            119.51              POLYOL B      37.05                                                                              36.89                                                                              36.62                                                                              36.51                                                                              36.35                                                                              36.24                                                                              36.09                                                                              35.96                                                                              35.8                                                                              35.78               POLYOL C      12.62                                                                              12.91                                                                              12.81                                                                              12.78                                                                              12.72                                                                              12.68                                                                              12.63                                                                              12.58                                                                              12.53                                                                             12.52               1,4-BUTANEDIOL                                                                              11.12                                                                              11.03                                                                              10.99                                                                              10.95                                                                              10.91                                                                              10.87                                                                              10.83                                                                              10.79                                                                              10.74                                                                             10.73               ETHYLENE GLYCOL                                                                             0.37 0.37 0.37 0.37 0.36 0.36 0.36 0.36 0.36                                                                              0.36                XFE-1028      2.38 2.36 2.34 2.32 2.3  2.29 2.27 2.25 2.24                                                                              2.27                T-12          0.048                                                                              0.047                                                                              0.046                                                                              0.046                                                                              0.048                                                                              0.049                                                                              0.045                                                                              0.045                                                                              0.044                                                                             0.045               WATER         --   0.094                                                                              0.19 0.28 0.37 0.457                                                                              0.545                                                                              0.631                                                                              0.7 0.18                FREON 11a     --   --   --   --   --   --   --   --   --  10.9                HFC-134a      4.58 4.1  3.6  3.35 2.65 1.73 1.13 0.45 --  --                  ISO A         70.56                                                                              71.92                                                                              73.31                                                                              74.68                                                                              75.95                                                                              77.20                                                                              78.48                                                                              79.72                                                                              78.75                                                                             70.17               PHYSICALS                                                                     SECTIONAL DENSITY (pcf)                                                                     29.4 28.93                                                                              28.73                                                                              27.57                                                                              26.83                                                                              26.79                                                                              25.79                                                                              25.18                                                                              25.64                                                                             29.62               TENSILE STRENGTH (psi)                                                                      199.3                                                                              153.6                                                                              160  211  230  119.6                                                                              117.3                                                                              126.3                                                                              179.6                                                                             149                 ELONGATION % AT BREAK                                                                       203.3                                                                              130  143.3                                                                              193.3                                                                              223  123.3                                                                              120  130  190 120                 SPLIT TEAR (pi)                                                                             36.9 38.9 35.7 32.3 30.6 28.9 25.15                                                                              31.75                                                                              31.1                                                                              41.25               GRAVES TEAR (pi)                                                                            67.9 80.5 79.9 69.1 65.6 56.6 55.65                                                                              53.9 63.15                                                                             73.45               SHORE HARDNESS                                                                              43   44   39   43   42   38   34   32   33  48                  TABER ABRASION                                                                              261.7                                                                              55   73.9 22.6 30.6 109.8                                                                              148.9                                                                              94   57.4                                                                              254.4               (mg. LOST, 18                                                                 WHEEL)                                                                        ROSS FLEX                                                                     K CYCLES TO FAIL                                                                            >100 >100 >100 78.7 64   10.6 9    14.8 16  >100                % CRACK AT FAIL                                                                             0    0    0    --   --   --   --   --   --  0                   __________________________________________________________________________     **    equals failure                                                     

All samples were prepared in the same manner. Predetermined amounts ofroom temperature isocyanate and resin mixture were added to a container.The components were stirred using a high speed mixer at about 3000 rpmfor eight to ten seconds. The contents were poured into a clean, dry12"×6"×3/8" plaque mold. The mold was shut, and the foam was allowed tocure. The finished plaque was demolded and tested.

Table 1 shows the effect of varying the isocyanate index on typicalformulation using HFC-134a as the sole blowing agent. Table 2illustrates the effects of various emulsifiers/surfactants compared withno surfactant (number 10). Table 3 illustrates a system co-blown withHFC-134a and water. Examples 9 and 10 are comparative examples. Example9 uses water as the sole blowing agent. Example 10 uses a combination ofwater and Freon 11a as a co-blowing system.

I claim:
 1. A method of making an integral skin polyurethane foamarticle comprising reacting:a) an organic polyisocyanate; with b) apolyoxyalkylene polyether polyol; and, c) one or more chain extenders,said one or more chain extenders consisting of compounds free of anaromatic nucleus;in the presence of d) a urethane-promoting catalyst;and, e) a blowing agent comprising 1,1,1,2-tetrafluoroethane.
 2. Themethod of claim 1, wherein the blowing agent consists of1,1,1,2-tetrafluoroethane or a mixture of 1,1,1,2-fluoroethane andwater.
 3. The method of claim 2, wherein the blowing agent consists of1,1,1,2-tetrafluoroethane.
 4. The method of claim 1, wherein thesurfactant comprises a fluoroaliphatic polymeric ester.
 5. The method ofclaim 1, further comprising a vinyl polymer grafted polyoxyalkylenepolyether dispersion.
 6. The method of claim 1, wherein the amount of1,1,1,2-tetrafluoroethane is from 1.5 to 6.0 percent by weight, based onthe weight of all non-isocyanate components.
 7. The method of claim 1,wherein the integral skin foam has a density of between of 25 to 35 pcf.